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How to identify it
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Most other soft scales in California | Keep their eggs hidden beneath the female's body instead of producing a cottony egg sac that spills out around the edges.[1] |
Where it lives
First described from Hawaii and now established in many tropical and subtropical countries, including mainland Spain and the Canary Islands in Europe. In California it infests mostly broadleaf landscape plants of subtropical and tropical origin.[2][1]
Biology and life cycle
It goes through egg, nymph and adult stages, with one generation a year. Nymphs stay fairly mobile and can move to other parts of the plant or to plants that touch it.[1]
It is highly polyphagous, recorded on about 230 plant species in more than 70 families. Favored hosts include avocado, citrus, coffee, guava, litchi, mango, mulberry and pomegranate, and it also feeds on tomato and pepper.[2]
Landscape hosts in California include anthurium, aralia, begonia, camellia, croton, ficus, hibiscus, gardenia, pittosporum, plumeria, schefflera, Schinus and Syzygium.[1]
Damage and signs
- It sucks phloem sap from leaves and thin-barked shoots. When abundant it produces large amounts of honeydew, on which blackish sooty mold grows.[1]
- Females cover plants with white egg sacs, and the wax can stay on the plant long after the scales have died, spoiling its appearance.[1]
- In Spain it has damaged Melia azedarach, an ornamental tree that lines streets in Valencia, and European plant-health experts expect losses in citrus, mango, mulberry, vegetable and ornamental crops if it spreads there.[2]
Health risk
The sources describe it only as a plant pest; none mentions any risk to people or pets.[1][2]
Control
Prevention
Help natural enemies by controlling ants, keeping dust down (for example by hosing off shrubs now and then) and avoiding broad-spectrum, persistent insecticides.[1]
Biological control
The mealybug destroyer is an important predator, and parasitic wasps also help when natural enemies are conserved.[1]
Pesticides
If control is still needed, thoroughly spray infested shoot tips with horticultural oil during the dormant season or when monitoring shows crawlers are active in spring.[1]
Common questions
- What is the white cottony material on my hibiscus or gardenia?
- It may be the egg sacs of green shield scale, a soft scale whose females produce wide cottony egg sacs that spill out around the edges of the body.[1]
- Why does the white wax stay after the scales are gone?
- The wax from old egg sacs can remain on plant surfaces long after the scales have died.[1]
- How do I control green shield scale?
- Conserve natural enemies such as the mealybug destroyer by controlling ants and avoiding persistent broad-spectrum insecticides; if needed, spray horticultural oil when crawlers are active or during the dormant season.[1]
Sources
- University of California Statewide IPM Program, “Green Shield Scale, UC IPM Home and Landscape.” ipm.ucanr.edu/home-and-landscape/green-shield-scale/ (accessed 2026-11-09)
- European Food Safety Authority (EFSA Journal), “Pest categorisation of Pulvinaria psidii (EFSA Panel on Plant Health 2022).” doi.org/10.2903/j.efsa.2022.7526 (accessed 2026-11-09)
- iNaturalist, “Pulvinaria psidii taxon page (order and family).” www.inaturalist.org/taxa/330207 (accessed 2026-11-09)